For the production of an alpha-olefin polymer, particularly an ethylene polymer or an ethylene/alpha-olfein copolymer, methods have previously been known in which ethylene is polymerized, or ethylene and an alpha-olefin are copolymerized, in the presence of a titanium-containing catalyst comprising a titanium compound and an organoaluminum compound or a vanadium-containing catalyst comprising a vanadium compound and an organoaluminum compound.
On the other hand, catalysts comprising a zirconium compound and an aluminoxane have been proposed recently as a new type of Ziegler catalyst for olefin polymerization.
Japanese Laid-Open Patent Publication No. 19309/1983 discloses a process which comprises polymerizing ethylene and at least one alpha-olefin having 3 to 12 carbon atoms at a temperature of -50.degree. C. to 200.degree. C. in the presence of a catalyst composed of a transition metal-containing catalyst represented by the following formula EQU (cyclopentadienyl).sub.2 MR.sup.1 Hal
wherein R.sup.1 represents cyclopentadienyl, C.sub.1 -C.sub.8 alkyl or halogen, M represents a transition metal, and Hal represents halogen, PA1 wherein R.sup.2 represents methyl or ethyl, and PA1 n is a number of 4 to 20, PA1 (A) a solid catalyst component composed of a compound of a transition metal of Group IVB of the periodic table supported on a carrier, and PA1 (B) an aluminoxane, PA1 (1) A method which comprises treating the carrier with an organoaluminum compound such as trimethylaluminum, dimethyl aluminum chloride and aluminoxane or a halogen-containing silicon compound such as trichlorosilane, and mixing the treated carrier with the Group IVB transition metal compound. PA1 (2) A method which comprises treating the Group IVB transition metal compound with an organoaluminum compound such as trimethylaluminum or dimethyl aluminum chloride and then mixing the treated compound with the carrier in the presence of an inert solvent. PA1 (3) A method which comprises mixing the carrier, the Group IVB transition metal compound and the aluminoxane as catalyst component (B), and removing the solvent from the mixture using an evaporator, for example, under atmospheric pressure or reduced pressure. PA1 wherein R.sup.7 represents an alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms, Z represents a halogen atom, and f is a number of 1 to 3, PA1 wherein Y represents a chlorine or bromine atom, R.sup.5 and R.sup.6, independently from each other, represent an alkyl group having 1 to 12 carbon atoms, an aryl group, or a cycloalkyl group having 3 to 12 carbon atoms, d is a number of 1 to 4, and e is a number of 0 to 4, provided that the total of d and e is a number of 1 to 4.
with a linear aluminoxane represented by the following formula EQU Al.sub.2 OR.sub.4.sup.2 (Al(R.sup.2)--O).sub.n
or a cyclic aluminoxane represented by the following formula ##STR1## wherein R.sup.2 and n are as defined above.
This patent document states that in order to adjust the density of the resulting polyethylene, ethylene should be polymerized in the presence of a small amount (up to 10% by weight) of a slightly long-chain alpha-olefin or a mixture thereof.
Japanese Laid-Open Patennt Publication No. 95292/1984 describes an invention relating to a process for producing a linear aluminoxane represented by the following formula ##STR2## wherein n is 2 to 40 and R.sup.3 is C.sub.1 -C.sub.8 alkyl, and a cyclic aluminoxane represented by the following formula ##STR3## wherein n and R are as defined above.
This Publication states that when an olefin is polymerized using a mixture of methylaluminoxane produced by the above process with a bis(cyclopentadienyl) compound of titanium or zirconium, polyethylene is obtained in an amount of at least 25 million grams per gram of the transition metal per hour.
Japanese Laid-Open Patent Publication No. 35005/1985 discloses a process for producing a catalyst for polymerization of olefins, which comprises reacting an aluminoxane compound represented by the following formula ##STR4## wherein R.sup.4 represents C.sub.1 -C.sub.10 alkyl, and
R.sup.o is R.sup.4 or is bonded to represent --O--, with a magnesium compound, then chlorinating the reaction product, and treating the chlorinated product with a compound of Ti, V, Zr or Cr. The above Publication describes that the above catalyst is especially suitable for the copolymerization of ethylene with a C.sub.3 -C.sub.12 alpha-olefin mixture.
Japanese Laid-Open Patent Publication No. 35006/1985 discloses a combination of (a) a mono-, di- or tri-pentadienyl compound of at least two dissimilar transition metals or its derivative with (b) alumoxane (aluminoxane) as a catalyst system for polymers blended in a reactor. Example 1 of this Publication discloses that polyethylene having a number average molecular weight of 15,300 and a weight average molecular weight of 36,400 and containing 3.4% of a propylene component was obtained by polymerizing ethylene and propylene using bis(pentamethylcyclopentadienyl) dimethyl zirconium and alumoxane as a catalyst. In Example 2 of this Publication, a blend consisting of polyethylene and an ethylene/propylene copolymer and having a number average molecular weight of 2,000, a weight average molecular weight of 8,300 and a propylene component content of 7.1 mole % and consisting of a toluene-soluble portion having a number average molecular weight of 2,200, a weight average molecular weight of 11,900 and a propylene component content of 30 mole % and a toluene-insoluble portion having a number average molecular weight of 3,000, a weight average molecular weight of 7,400 and a propylene component content of 4.8 mole % was obtained by polymerizing ethylene and propylene using bis(pentamethylcyclopentadieneyl)zirconium dichloride, bis(methylcyclopentadienyl)zirconium dichloride and alumoxane as a catalyst. Likewise, Example 3 of this Publication describes a blend of LLDPE and an ethylene/propylene copolymer composed of a soluble portion having a molecular weight distribution (Mw/Mn) of 4.57 and a propylene component content of 20.6 mole % and an insoluble portion having a molecular weight distribution of 3.04 and a propylene component content of 2.9 mole %.
Japanese Laid-Open Patent Publication No. 35007/1985 describes a process which comprises polymerizing ethylene alone or with an alpha-olefin having at least 3 carbon atoms in the presence of a catalyst system comprising a metallocene and a cyclic alumoxane represented by the following formula ##STR5## wherein R.sup.5 represents an alkyl group having 1 to 5 carbon atoms, and n is an integer of 1 to about 20,
or a linear alumoxane represented by the following formula ##STR6## wherein R.sup.5 and n are as defined above. The Publication describes that the polymer obtained by the above process has a weight average molecular weight of about 500 to about 1,400,000 and a molecular weight distribution of 1.5 to 4.0.
Japanese Laid-Open Patent Publication No. 35008/1985 describes that polyethylene or a copolymer of ethylene and a C.sub.3 -C.sub.10 alpha-olefin having a wide molecular weight distribution is produced by using a catalyst system comprising at least two types of metallocenes and alumoxane. The Publication states that the above copolymer has a molecular weight distribution (Mw/Mn) of 2 to 50.
These catalysts formed from transition metal compounds and aluminoxanes have much higher polymerization activity than the catalyst systems known heretofore.
On the other hand, methods using catalysts formed from solid catalyst components composed of the above transition metal compounds supported on porous inorganic oxide carriers such as silica, silica-alumina and alumina and aluminoxanes are proposed in Japanese Laid-Open Patent Publications Nos. 35006/1985, 35007/1985 and 35008/1985 which are cited above. Japanese Laid-Open Patent Publications Nos. 31404/1986, 108610/1986 and 106808/1985 propose methods using solid catalyst components supported on similar porous inorganic oxide carriers.
It is an object of this invention to provide a catalyst for polymerizing alpha-olefins, which has excellent polymerization activity and gives an ethylene polymer or an ethylene/alpha-olefin copolymer having excellent powder characteristics and a narrow molecular weight distribution or composition distribution, and when applied to the copolymerization of at least two olefins, gives an olefin copolymer having a narrow molecular weight distribution and composition distribution.
Another object of this invention is to provide a process for producing an ethylene polymer or an ethylene/alpha-olefin copolymer having the aforesaid properties by polymerizing or copolymerizing alpha-olefins using the catalyst of this invention.
According to this invention, these objects and advantages are firstly achieved by a catalyst for polymerization of alpha-olefins, said catalyst being formed by using a solid catalyst comprising
in pre-polymerization of an olefin.
The catalyst of this invention is formed from the solid catalyst component (A) and the aluminoxane (B).
The catalyst component (A) is a solid catalyst component composed of a compound of a transition metal of Group IVB of the periodic table supported on a carrier.
The transition metal of Group IVB of the periodic table in the catalyst component (A) is preferably selected from the group consisting of titanium, zirconium and hafnium. Titanium and zirconium are more preferred, and zirconium is especially preferred.
The compound of a transition metal of Group IVB of the periodic table in the catalyst component (A) preferably has a group having a conjugated .pi. electron as a ligand.
Examples of the transition metal compound having a group with a conjugated .pi. electron as a ligand are compounds represented by the following formula (I) EQU R.sub.k.sup.1 R.sub.l.sup.2 R.sub.m.sup.3 R.sub.n.sup.4 M (I)
wherein R.sup.1 represents a cycloalkadienyl group, R.sup.2, R.sup.3 and R.sup.4 are identical or different and each represents a cycloalkadienyl group, an aryl group, an alkyl group, a cycloalkyl group, an aralkyl group, a halogen atom, a hydrogen atom, or a group of the formula --OR.sup.a, --SR.sup.b or --NR.sub.2.sup.c in which each of R.sup.a, R.sup.b and R.sup.c represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an organic silyl group, M represents zirconium, titanium or hafnium, k is 1, 2, 3 or 4, l, m and n are each 0, 1, 2 or 3, and k+l+m+n=4.
Examples of the cycloalkadienyl group represented by R.sup.1 are a cyclopentadienyl group, a methylcyclopentadienyl group, an ethylcyclopentadienyl group, a dimethylcyclopentadienyl group, an indenyl group and a tetrahydroindenyl group. Examples of the cycloalkadienyl group represented by R.sup.2, R.sup.3 and R.sup.4 may be the same as above.
The aryl group represented by R.sup.2, R.sup.3 and R.sup.4 is preferably a phenyl or tolyl group, for example.
Likewise, preferred examples of the aralkyl group are benzyl and neophile groups.
Examples of preferred alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, 2-ethylhexyl, decyl and oleyl groups.
Preferably, the cycloalkyl group may be, for example, a cyclopentyl, cyclohexyl, cyclooctyl, or norbornyl group.
The halogen atom may be, for example, fluorine, chlorine or bromine.
Specific examples of the groups --OR.sup.a, --SR.sup.b and --NR.sub.2.sup.c where R.sup.a, R.sup.b and R.sup.c are alkyl cycloalkyl, aryl and aralkyl will be clear from the above specific examples of these groups.
Examples of the organic silyl group for R.sup.a, R.sup.b and R.sup.c are trimethylsilyl, triethylsilyl, phenyldimethylsilyl, diphenylmethylsilyl and triphenylsilyl groups.
Examples of zirconium compounds corresponding to formula (I) in which Me is zirconium are listed below:
bis(cyclopentadienyl) zirconium monochloride monohydride,
bis(cyclopentadienyl)zirconium monobromide monohydride,
bis(cyclopentadienyl)methylzirconium hydride,
bis(cyclopentadienyl)ethylzirconium hydride,
bis(cyclopentadienyl)cyclohexylzirconium hydride,
bis(cyclopentadienyl)phenylzirconium hydride,
bis(cyclopentadienyl)benzylzirconium hydride,
bis(cyclopentadienyl)neopentylzirconium hydride,
bis(methylcyclopentadienyl)zirconium monochloride monohydride,
bis(indenyl)zirconium monochloride monohydride,
bis(cyclopentadienyl)zirconium dichloride,
bis(cyclopentadienyl)zirconium dibromide,
bis(cyclopentadienyl)methylzirconium monochloride,
bis(cyclopentadienyl)ethylzrconium monochloride,
bis(cyclopentadienyl)cyclohexylzirconium monochloride,
bis(cyclopentadienyl)phenylzirconium monochloride,
bis(cyclopentadienyl)benzylzirconium monochloride,
bis(methylcyclopentadienyl)zirconium dichloride,
bis(indenyl)zirconium dichloride,
bis(indenyl)zirconium dibromide,
bis(cyclopentadienyl)diphenylzirconium,
bis(cyclopentadienyl)benzylzirconium,
bis(cyclopentadienyl)methoxyzirconium chloride,
bis(cyclopentadienyl)ethoxyzirconium chloride,
bis(cyclopentadienyl)butoxyzirconium chloride,
bis(cyclopentadienyl)2-ethylhexoxyzirconium chloride,
bis(cyclopentadienyl)methylzirconium ethoxide,
bis(cyclopentadienyl)methylzirconium butoxide,
bis(cyclopentadienyl)ethylzirconium ethoxide,
bis(cyclopentadienyl)phenylzirconium ethoxide,
bis(cyclopentadienyl)benzylzirconium ethoxide,
bis(methylcyclopentadienyl)ethoxyzirconium chloride,
bis(indenyl)ethoxyzirconium chloride,
bis(cyclopentadienyl)ethoxyzirconium,
bis(cyclopentadienyl)butoxyzirconium,
bis(cyclopentadienyl)2-ethylhexoxyzirconium,
bis(cyclopentadienyl)phenoxyzirconium chloride,
bis(cyclopentadienyl)cyclohexoxyzirconium chloride,
bis(cyclopentadienyl)phenylmethoxyzirconium chloride,
bis(cyclopentadienyl)methylzirconium phenylmethoxide,
bis(cyclopentadienyl)trimethylsiloxyzirconium chloride,
bis(cyclopentadienyl)triphenylsiloxyzirconium chloride,
bis(cyclopentadienyl)thiophenylzirconium chloride,
bis(cyclopentadienyl)thioethylzirconium chloride,
bis(cyclopentadienyl)bis(dimethylamide)zirconium,
bis(cyclopentadienyl)diethylamidezirconium chloride,
ethylenebis(indenyl)ethoxyzirconium chloride,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)ethoxyzirconium chloride,
ethylenebis(indenyl)dimethylzirconium,
ethylenebis(indenyl)diethylzirconium,
ethylenebis(indenyl)dibenzylzirconium,
ethylenebis(indenyl)methylzirconium monobromide,
ethylenebis(indenyl)ethylzirconium monochloride,
ethylenebis(indenyl)benzylzirconium monochloride,
ethylenebis(indenyl)methylzirconium monochloride,
ethylenebis(indenyl)zirconium dichloride,
ethylenebis(indenyl)zirconium dibromide,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethylzirconium,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methylzirconium monochloride,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dibromide,
ethylenebis(4-methyl-1-indenyl)zirconium dichloride,
ethylenebis(5-methyl-1-indenyl)zirconium dichloride,
ethylenebis(6-methyl-1-indenyl)zirconium dichloride,
ethylenebis(7-methyl-1-indenyl)zirconium dichloride,
ethylenebis(5-methoxy-1-indenyl)zirconium dichloride,
ethylenebis(2,3-dimethyl-1-indenyl)zirconium dichloride,
ethylenebis(4,7-dimethyl-1-indenyl)zirconium dichloride,
ethylenebis(4,7-dimethoxy-1-indenyl)zirconium dichloride,
ethylenebis(indenyl)zirconium dimethoxide,
ethylenebis(indenyl)zirconium diethoxide,
ethylenebis((indenyl)methoxyzirconium chloride,
ethylenebis(indenyl)ethoxyzirconium chloride,
ethylenebis(indenyl)methylzirconium ethoxide,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dimethoxide,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium diethoxide,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methoxyzirconium chloride
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)ethoxyzirconium chloride, and
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methylzirconium ethoxide.
Examples of titanium compounds corresponding to formula (I) in which Me is titanium are listed below:
bis(cyclopentadienyl)titanium monochloride monohydride,
bis(cyclopentadienyl)methyltitanium hydride,
bis(cyclopentadienyl)phenyltitanium chloride,
bis(cyclopentadienyl)benzyltitanium chloride,
bis(cyclopentadienyl)titanium chloride,
bis(cyclopentadienyl)dibenzyltitanium,
bis(cyclopentadienyl)ethoxytitanium chloride,
bis(cyclopentadienyl)butoxytitanium chloride,
bis(cyclopentadienyl)methyltitanium ethoxide,
bis(cyclopentadienyl)phenoxytitanium chloride,
bis(cyclopentadienyl)trimethylsiloxytitanium chloride,
bis(cyclopentadienyl)thiophenyltitanium chloride,
bis(cyclopentadienyl)bis(dimethylamide)titanium,
bis(cyclopentadienyl)ethoxytitanium,
ethylenebis(indenyl)titanium dichloride, and
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride.
Examples of hafnium compounds corresponding to formula (I) in which Me is hafnium are listed below:
bis(cyclopentadienyl)hafnium monochloride monohydride,
bis(cyclopentadienyl)ethylhafnium hydride,
bis(cyclopentadienyl)phenylhafnium chloride,
bis(cyclopentadienyl)hafnium dichloride,
bis(cyclopentadienyl)hafnium dibenzil
bis(cyclopentadienyl)ethoxyhafnium chloride,
bis(cyclopentadienyl)butoxyhafnium chloride,
bis(cyclopentadienyl)methylhafnium ethoxide,
bis(cyclopentadienyl)phenoxyhafnium chloride,
bis(cyclopentadienyl)thiophenylhafnium chloride,
bis(cyclopentadienyl)bis(diethylamide)hafnium,
ethylenebis(indenyl)hafnium dichloride, and
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium dichloride.
In the catalyst component (A), the IVB transition metal compound may be treated with an organic metal compound prior to supporting. The organic metal compound may be, for example, an organoaluminum compound, an organoboron compound, an organomagnesium compound, an organozinc compound or an organolithium compound. The organoaluminum compound is preferred.
Examples of the organoaluminum compound include trialkylaluminums such as trimethylaluminum, triethylaluminum and tributylaluminum; alkenylaluminums such as isoprenylaluminum; dialkyl aluminum alkoxides such as dimethyl aluminum methoxide, diethyl aluminum ethoxide and dibutyl aluminum butoxide; alkyl aluminum sesquialkoxides such as methyl aluminum sesquimethoxide and ethyl aluminum sesquiethoxide; partially alkoxylated alkylaluminums having an average composition of the formula R.sub.2.5.sup.1 Al(OR.sup.2).sub.0.5 ; dialkyl aluminum halides such as dimethyl aluminum chloride, diethyl aluminum chloride and dimethyl aluminum bromide; alkyl aluminum sesquihalides such as methyl aluminum sesquichloride and ethyl aluminum sesquichloride; partially halogenated alkylaluminums, for example alkyl aluminum dihalides such as methyl aluminum dichloride and ethyl aluminum dichloride.
The trialkylaluminums and dialkyl aluminum chlorides are preferred, and above all trimethylaluminum, triethylaluminum and dimethyl aluminum chloride are preferred.
Triethylboron is a preferred example of the organoboron compound.
Examples of the organomagnesium compound are ethylbutylmagnesium, di-n-hexylmagnesium, ethyl magnesium bromide, phenyl magnesium bromide and benzyl magnesium chloride.
Diethylzinc is a preferred example of the organozinc compound.
Methyllithium, butyllithium and phenyllithium are examples of the organolithium compound.
In the catalyst of this invention, the solid catalyst component (A) is composed of the compound of the transition metal of Group IVB of the periodic table supported on a carrier.
The carrier may be organic or inorganic, and is advantageously a granular or particulate solid having a particle diameter of, for example, 10 to 300 micrometers, preferably 20 to 200 micrometers. A porous oxide is preferred as the inorganic carrier. Specific examples include SiO.sub.2, Al.sub.2 O.sub.3, MgO, ZrO.sub.2, TiO.sub.2, B.sub.2 O.sub.3, CaO, ZnO, BaO and ThO.sub.2 and mixtures of these, such as SiO.sub.2 --MgO, SiO.sub.2 --Al.sub.2 O.sub.3, SiO.sub.2 --TiO.sub.2, SiO.sub.2 --V.sub.2 O.sub.5, SiO.sub.2 --Cr.sub.2 O.sub.3 and SiO.sub.2 --TiO.sub.2 --MgO. A catalyst containing at least one component selected from the group of SiO.sub.2 and Al.sub.2 O.sub.3 as a main component is preferred.
The inorganic oxide may contain a small amount of a carbonate, nitrate, sulfate or an oxide component such as Na.sub.2 CO.sub.3, K.sub.2 CO.sub.3, CaCO.sub.3, MgCO.sub.3, Na.sub.2 SO.sub.4, Al.sub.2 (SO.sub.4).sub.3, BaSO.sub.4, KNO.sub.3, Mg(NO.sub.3).sub.2, Al(NO.sub.3).sub.3, Na.sub.2 O, K.sub.2 O and Li.sub.2 O.
The porous inorganic carrier preferably used in this invention has a specific surface area of 50 to 1000 m.sup.2 /g, preferably 100 to 700 m.sup.2 /g and a pore volume of 0.3 to 2.5 cm.sup.2 /g, although its characteristics vary depending upon its type and the method of production. The carrier is used after it is calcined usually at 150.degree. to 1000.degree. C., preferably 200.degree. to 800.degree. C.
Granular or particulate solids of organic compounds having a particle diameter of 10 to 300 micrometers may also be used in the present invention. Examples of the organic compounds are (co)polymers containing alpha-olefins having 2 to 14 carbon atoms such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-decene as a main component, and polymers or copolymers containing vinylcyclohexane or styrene as a main component.
The mixing weight ratio of the Group IVB transition metal compound to the carrier (transition metal/carrier) in the supporting reaction in this invention is 0.5 to 15%, preferably 0.8 to 10% by weight, more preferably 1 to 7% by weight.
The supporting may be carried out, for example, by mixing the carrier and the transition metal compound in the presence of an inert solvent, and removing the solvent by using an evaporator, for example, at room temperature or at an elevated temperature under atmospheric pressure or elevated pressure.
It can also be achieved by the following methods, for example.
The catalyst component (B) is an aluminoxane. The aluminoxane used as the catalyst component (B) may be, for example, an organoaluminum compound represented by the following formula (II) ##STR7## wherein R represents a hydrocarbon group, X represents a halogen atom, and a and b, independently from each other, are a number of 0 to 80 provided that a and b are not simultaneously zero (in this formula, a+b+2 is the degree of polymerization),
or by the following formula ##STR8## wherein R, X, a, and b are as defined with regard to formula (II) above (in this formula, a+b is the degree of polymerization).
In the above formulae (II) and (III), R represents a hydrocarbon group such as an alkyl, cycloalkyl, aryl or aralkyl group. The alkyl group is preferably a lower alkyl group such as a methyl, ethyl, propyl or butyl group. The cycloalkyl group is preferably a cyclopentyl or cyclohexyl group. The aryl group is preferably a phenyl or tolyl group. Benzyl and neophile groups are preferred examples of the aralkyl group. Among them, the alkyl groups are especially preferred.
X is a halogen atom such as fluorine, chlorine, bromine or iodine. Chlorine is especially preferred.
a and b, independently from each other, represent a number of 0 to 80, provided that a and b are not simultaneously zero.
When b is 0, formula (II) can be written as (II)-1 ##STR9## wherein R and a are as defined above.
The formula (III) above may be written as the following formula (III)-1 ##STR10## wherein R and a are as defined above.
In formula (II)-1, a is preferably 2 to 50, more preferably 4 to 30. In formula (III)-1, a is preferably 4 to 52, more preferably 6 to 32.
a is preferably 0 to 40, more preferably 3 to 30, and b is preferably 1 to 40, more preferably 3 to 30.
The a+b value is preferably 4 to 50, more preferably 8 to 30.
In formulae (II) and (III), the two units --O--Al and ##STR11## may be bonded in blocks or at random.
When a is 0 in formulae (II) and (III), it is desirable to use an organoaluminum compound of the following formula (V) EQU AlR.sub.f.sup.7 Z.sub.3-f (V)
together with the halogenated aluminoxane. Examples of the organoaluminum compound are trimethylaluminum, triethylaluminum, tributylaluminum, trihexylaluminum, diethylaluminum chloride and ethyl aluminum sesquichloride.
At this time, it is desirable to use 0.1 to 10 moles, preferably 0.3 to 3.0 moles, especially preferably 0.5 to 2.0 moles, of the organoaluminum compound per mole of the aluminum atom of the halogenated aluminoxane.
The following methods may be cited as examples of producing the aluminoxane or the halogenated aluminoxane.
(1) A method which comprises reacting a compound containing water of adsorption or a salt containing water of crystallization, such as magnesium chloride hydrate, nickel sulfate hydrate or cerous chloride hydrate, with a trialkylaluminum or a dialkyl aluminum monohalide while the former is being suspended in a medium such as benzene, toluene, ethyl ether or tetrahydrofuran.
(2) A method which comprises the action of water directly on a trialkylaluminum and/or a dialkyl aluminum monohalide in a medium such as benzene, toluene, ethyl ether or tetrahydrofuran.
Of these, the method (1) is preferably employed. The aluminoxane may contain a small amount of an organometallic component.
The catalyst of this invention may be prepared by contacting the prepared carrier-supported solid catalyst component (A) and aluminoxane catalyst component (B) in an inert medium, or by supporting the Group IVB transition metal compound and the aluminoxane simultaneously on a carrier, prior to pre-polymerization. Preferably, prior to pre-polymerization, the catalyst components (A) and (B) are mixed in an inert hydrocarbon medium. When the inert hydrocarbon medium dissolves the catalyst component (B), the resulting mixture is preferably subjected to an evaporator at room temperature or at an elevated temperature under atmospheric or reduced pressure to remove the solvent. It is alternatively preferred to deposit the catalyst component (B) by, for example, adding a solvent in which the catalyst component (B) is insoluble, thereby to form a solid catalyst at least comprising (A) and (B).
The catalyst of this invention contains the transition metal compound in an amount of usually 0.003 to 3 mg-atom, preferably 0.005 to 2 mg-atom, especially preferably 0.01 to 1 mg-atom, as the transition metal atom per gram of the carrier. The proportion of the aluminoxane catalyst component, whether prior to the pre-polymerization of an olefin, the catalyst is a solid catalyst formed from the components (A) and (B) in an inert hydrocarbon medium or a solid catalyst formed by supporting the transition metal component and the aluminoxane catalyst component, is such that the atomic ratio of aluminum atom to the transition metal atom of the transition metal compound (Al/M) is from 1 to 1000, preferably from 10 to 700, especially preferably from 15 to 500.
The catalyst of this invention may contain an electron donor in addition to the carrier component, transition metal compound and the aluminoxane. Examples of the electron donor include carboxylic acids, esters, ethers, ketones, aldehydes, alcohols, phenols, acid amides, oxygen-containing compounds such as compounds containing a metal--O--C bond (the metal is, for example, aluminum or silicon), nitriles, amines, and phosphines. The proportion of the electron donor is usually 0 to 1 mole, preferably 0.1 to 0.6 mole, per gram of the transition metal atom (M).
The solid catalyst component in this invention has an average particle diameter of usually 10 to 300 micrometers, preferably 20 to 200 micrometers, more preferably 25 to 100 micrometers and a specific surface area of usually 20 to 1000 m.sup.2 /g, preferably 50 to 500 m.sup.2 /g, specially preferably 100 to 300 m.sup.2 /g.
The catalyst of this invention is formed by pre-polymerizing an olefin in the presence of the solid catalyst component formed from the catalyst components (A) and (B) prior to the main polymerization of an olefin. The pre-polymerization is carried out by polymerizing 0.05 to 30 g, preferably 0.1 to 20 g, more preferably 0.2 to 10 g, of the olefin per gram of the solid catalyst component formed from the catalyst components (A) and (B). Examples of the olefin are ethylene, and alpha-olefins having 3 to 20 carbon atoms such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-tetradecene. Ethylene is especially preferred.
The pre-polymerization is carried out (1) in the absence of a solvent, or (2) in an inert hydrocarbon medium. The mole ratio of the aluminum atom of the catalyst component (B) to the transition metal atom of the catalyst component (A) (Al/transition metal atom) in the pre-polymerization treatment is from 1 to 1000, preferably from 10 to 700, more preferably from 15 to 500. The pre-polymerization temperature is from -20.degree. C. to 70.degree. C., preferably -10.degree. C. to 60.degree. C., more preferably 0.degree. C. to 50.degree. C.
The pre-polymerization treatment may be carried out batchwise or continuously under reduced, atmospheric or elevated pressure. A molecular weight controlling agent such as hydrogen may be caused to be present in the pre-polymerization. Its amount, however, is preferably limited to those values in which a prepolymer having an intrinsic viscosity [.eta.], measured in decalin at 135.degree. C., of at least 0.2 dl/g, preferably 0.5 to 20 dl/g, can be produced.
By using the catalyst of this invention described above, alpha-olefins can be advantageously polymerized or copolymerized.
Investigations of the present inventors have shown that when a porous inorganic oxide treated with a compound selected from the group consisting of organometallic compounds, halogen-containing silicon compounds and aluminoxanes is used as a carrier for the solid catalyst component (A) in the catalyst component (A) and the alumilnoxane (B) before pre-polymerization treatment, the resulting catalyst shows excellent activity equivalent to the catalyst of this invention without subjecting it to pre-polymerization treatment.
Accordingly, the objects and advantages of the present invention are achieved secondly by a catalyst for polymerization of alpha-olefins, said catalyst comprising
(A') a solid catalyst component composed of a compound of a transition metal of Group I of the periodic table supported on a porous inorganic oxide carrier treated with a compound selected from the group consisting of organometallic compounds, halogen-containing silicon compounds and aluminoxanes, and
(B) an aluminoxane.
In the catalyst of this invention for polymerization of alpha-olefins, the porous inorganic oxide carrier is treated with a compound selected from the group consisting of organometallic compounds, halogen-containing silicon compounds and aluminoxanes.
The porous inorganic oxide carrier may be any of those which are exemplified hereinabove.
The organometallic compounds as the treating agent may be the same as those exemplified hereinabove.
In the above treatment, the mixing ratio of the organometallic compound to the carrier, as the ratio of the millimoles of the organometallic compound to the grams of the carrier, is from 0.5 to 50, preferably from 1 to 30, preferably from 1.5 to 20.
The treatment of the porous inorganic oxide carrier with the organometallic compound in the catalyst component (A') may be carried out by dispersing the carrier in an inert solvent, adding at least one organometallic compound mentioned above, and maintaining the mixture at a temperature of 0.degree. to 120.degree. C., preferably 10.degree. to 100.degree. C., more preferably 20.degree. to 90.degree. C., for a period of 10 minutes to 10 hours, preferably 20 minutes to 5 hours, more preferably 30 minutes to 3 hours, under atmospheric, reduced or elevated pressure.
Examples of the inert solvent are aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbon such as pentane, hexane and isooctane, and alicyclic hydrocarbons such as cyclohexane.
The Group IVB transition metal compound is supported in a proportion of 3.times.10.sup.-3 to 3 mg-atom, preferably 5.times.10.sup.-3 to 2 mg-atom, more preferably 1.times.10.sup.-2 to 1 mg-atom, as the transition metal atom, per gram of the porous inorganic oxide carrier treated with the organometallic compound.
The supporting of the transition metal compound may be carried out by, for example, adding the porous inorganic oxide carrier treated with the organometallic compound and the transition metal compound in an inert hydrocarbon medium, and working up the mixture in the following manner.
The treating temperature is usually 0.degree. to 100.degree. C., preferably 20.degree. to 90.degree. C., and the treating time is usually 5 minutes to 5 hours, preferably 10 minutes to 2 hours. After the supporting, the inert hydrocarbon medium is removed by filtration or evaporated under atmospheric or reduced pressure to give a solid catalyst component.
Preferably, the halogen-containing silicon compound as the treating agent is, for example, a compound represented by the following formula (IV) EQU SiY.sub.d R.sub.e.sup.5 (OR.sup.6).sub.4-d-e (IV)
Examples of this compound include silicon tetrachloride, silicon tetrabromide, silicon trichloride, methylsilicon trichloride, ethylsilicon trichloride, propylsilicon trichloride, phenylsilicon trichloride, cyclohexylsilicon trichloride, silicon tribromide, ethylsilicon tribromide, dimethylsilicon dichloride, methylsilicon dichloride, phenylsilicon dichloride, methoxysilicon trichloride, ethoxysilicon trichloride, propoxysilicone trichloride, phenoxysilicon trichloride, ethoxysilicon tribromide, methoxysilicon dichloride, methoxysilicon dichloride, and silanol trichloride. They may be used singly or in combination. Among them, silicon tetrachloride, silicon trichloride and methylsilicon trichloride are preferred.
The mixing ratio of the halogen-containing silicon compound and the porous inorganic oxide in the above treatment is such that the proportion of the halogen-containing silicon compound is 0.001 to 10 moles, preferably 0.01 to 5 moles, more preferably 0.05 to 1 mole, per gram of the carrier compound. Preferably, after the treatment, the liquid portion containing the excess of the halogen-containing silane compound, for example is removed from the reaction mixture by filtration, decantation or the like.
In the preparation of the catalyst component (A'), the treatment of the porous inorganic oxide carrier with the halogen-containing silicon compound is carried out at a temperature of -50.degree. to 200.degree. C., preferably 0.degree. to 100.degree. C., more preferably 20.degree. to 70.degree. C., for a period of 10 minutes to 10 hours, preferably 20 minutes to 5 hours, under atmospheric, reduced or elevated pressure.
In the above treatment, an inert solvent may be used. Examples of the inert solvent are aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as pentane, hexane, isooctane, decane and dodecane, alicyclic hydrocarbons such as cyclohexane, and halogenated hydrocarbons such as chlorobenzene and ethylene dichloride.
In the preparation of the catalyst component (A'), if the Group IVB transition metal compound to be supported on the porous inorganic oxide carrier treated with the halogen-containing silane compound in the catalyst component (A') is liquid, it is not necessary to use an inert solvent. When the transition metal compound is a normally solid substance, it is generally preferred to use an inert solvent capable of dissolving the transition metal compound.
The inert solvent that can be used at this time may be the same as those exemplified hereinabove with regard to the treatment of the porous inorganic oxide carrier. Aromatic hydrocarbons such as benzene and toluene and halogenated hydrocarbons such as chlorobenzene are especially preferred.
The amount of the transition metal compound used in the above supporting reaction is preferably 0.001 to 500 millimoles, preferably 0.01 to 100 millimoles, especcally preferably 0.1 to 50 millimoles, per gram of the porous inorganic oxide carrier treated with the halogen-containing silane compound.
The amount of the inert solvent used in the above supporting reaction is 0.5 to 1000 ml, preferably 1 to 100 ml, especially preferably 2 to 50 ml, per gram of the porous inorganic oxide carrier treated with the halogen-containng silane compound.
The above supporting reaction may be carried out by contacting and mixing the transition metal compound with the porous inorganic oxide carrier treated with the halogen-containing silane compound at a temperature of 0.degree. to 200.degree. C., preferably 0.degree. to 100.degree. C., especially 20.degree. to 80.degree. C., for 1 minute to 10 hours, 5 minutes to 5 hours, or 10 minutes to 3 hours.
After the supporting reaction is carried out by the above method, the liquid portion of the reaction mixture is removed by, for example, filtration or decantation, and preferably the residue is washed several times with an inert solvent.
The solid catalyst component (A') prepared by the above method contains the transition metal compound in an amount of usually 0.005 to 5 millimoles, preferably 0.01 to 1 millimole, especially preferably 0.03 to 0.3 millimole, per gram of the component (A').
Examples of the aluminoxanes as the treating agent may be the same as those exemplified above as the catalyst component (B).
In the treatment of the porous inorgnaic oxide carrier with the alumioxane, the mixing ratio of both is such that the proportion of the aluminoxane is 0.001 to 100 millimoles, preferably 0.01 to 10 millimoles, preferably 0.05 to 5 millimoles, per gram of the carrier compound. Preferably, the liquid portion containing the excess of the aluminoxane after the above treatment is removed from the reaction mixture by such a method as filtration or decantation.
The treatment of the porous inorganic oxide carrier with the aluminoxane in the preparation of the catalyst component (A') may be carried out at a temperature of -50.degree. to 200.degree. C., preferably 0.degree. to 100.degree. C., more preferably 20.degree. to 70.degree. C. under atmospheric, reduced or elevated pressure for a period of 10 minutes to 10 hours, preferably 20 minutes to 5 hours.
The above treatment is preferably carried out in an inert solvent. Examples of the inert solvent may include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as pentane, hexane, isooctane, decane and dodecane, alicyclic hydrocarbons such as cyclohexane and halogenated hydrocarbons such as chlorobenzene and ethylene dichloride. Of these, the aromatic hydrocarbons are preferred.
When the Group IVB transition metal compound is liquid in depositing it on the porous inorganic oxide carrier treated with the aluminoxane, an inert solvent may or may not be used. When the transition metal compound is a normally solid substance, it is generally preferred to use an inert solvent capable of dissolving the transition metal compound.
The inert solvent that can be used at this time may be the same as those used in treating the porous inorganic oxide carrier with the aluminoxane. Aromatic hydrocarbons such as benzene and toluene and halogenated hydrocarbons such as chlorobenzene are especially preferred.
The amount of the transition metal compound used in the above supporting reaction is 0.001 to 10 millimoles, preferably 0.005 to 5 millimoles, especially preferably 0.01 to 1 millimole, per gram of the porous inorganic oxide carrier treated with the aluminoxane.
The amount of the inert solvent, the reaction temperature, the reaction time and the after-treatment used in the above supporting reaction may be the same as those described above with regard to the porous inorganic oxide carrier treated with the halogen-containing silicon compound.
The solid catalyst component (A') prepared by the above method contains the transition metal compound in an amount of usually 0.005 to 5 millimoles, preferably 0.01 to 1 millimole, especially preferably 0.03 to 0.3 millimole, per gram of the component (A').
The above catalyst of this invention comprises the solid catalyst component (A') prepared as above and the aluminoxane (B).
The catalyts of the invention described above can be used advantageously in the homopolymerization or copolymerization of alpha-olefins, and are particularly effective for the production of an ethylene polymer and a copolymer of ethylene and an alpha-olefin. Examples of the olefins that can be used in this invention are ethylene and alpha-olefins having 3 to 20 carbon atoms such as 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene.
In the process of this invention, olefin polymerization is usually carried out in the vapor phase or the liquid phase, for example in slurry. In the slurry polymerization, an inert hydrocarbon may be used as a solvent, or an olefin itself may be used as the solvent.
Specific examples of the hydrocarbon medium include aliphatic hydrocarbons such as butane, isobutane, pentane, hexane, octane, decane, dodecane, hexadecane and octadecane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and cyclooctane; aromatic hydrocarbons such as benzene, toluene and xylene; and petroleum fractions such as gasoline, kerosene and light oil. Of these, the aliphatic hydrocarbons, alicyclic hydrocarbons and petroleum fractions are preferred.
In carrying out slurry polymerization in the process of this invention, the polymerization temperature is usually -50.degree. to 120.degree. C., preferably 0.degree. to 100.degree. C.
In carrying out the process of this invention by a slurry or vapor-phase polymerization technique, the proportion of the transition metal compound is usually 10.sup.-8 to 10.sup.-2 gram-atom/liter, preferably 10.sup.-7 to 10.sup.-3 gram-atom/liter, as the concentration of the transition metal atom in the polymerization reaction system.
In the main polymerization reaction, the aluminoxane may, or may not, be used additionally. But to obtain a polymer having excellent powder characteristics, it is preferred not to use the aluminoxane additionally.
The polymerization pressure is usually atmospheric pressure to an elevated pressure of 100 kg/cm.sup.2, preferably 2 to 50 kg/cm.sup.2. The polymerization may be carried out batchwise, semi-continuously or continuously.
The polymerization may also be carried out in two or more steps in which the reaction conditions are different.
When a slurry polymerization technique or a vapor-phase polymerization technique is employed in the polymerization of olefins, particularly the polymerization of ethylene or the polymerization of ethylene with an alpha-olefin, no polymer adhesion to the reactor occurs, and a polymer having excellent powder characteristics and a narrow molecular distribution can be obtained. In particular, when the catalyst of this invention is applied to the copolymerization of two or more olefins, an olefin copolymer having a narrow molecular weight distribution and a narrow composition distribution can be obtained.